Implant devices, such as vertebral spacers, intravertebral or intervertebral fusion devices and disc replacement devices, have been developed to assist with stabilization and fixation or functional support of the spine. Examples include pre-assembled rings, cages, boxes, dowels, and wedges of varying size and construction, such as meshes or plates, movable disc surfaces, gel or polymer spacers, elastomers and structures. However, all existing devices have certain drawbacks, such as difficulty of construction, insertion, bulkiness, inadequate surface coverage in area and/or height, multiple sizes (inventory) and others.
PCT/US2012/045495 to Levy et al. describes devices for use in the spine as an expandable cage for spine fusion and for intra-vertebral use for VCF (vertebral compression fracture) repair. Other embodiments see use as a disc replacement device, a dynamic application allowing movement. The devices include MIS (minimal invasive surgery)/cannulated (or not cannulated) devices delivered over a guide wire, with expandable capability for height control (to regain disc space height or vertebral body height). Some devices include units connected like a train, which are installed with a delivery system that can be manipulated for positioning and sequential deployment of one or more units or deployment of the train as a whole. The train-style units can be a closed structure, e.g., a sleeve or a tube in the shape of a closed ring, or an open structure.